Variable heat-exchange system

ABSTRACT

A heat-exchange system involving heat-exchange coils adapted to be immersed in a body of liquid to effect heat exchange through the coils between the liquid and the fluid flowing through the coils. The heat-exchange coils are covered by an inverted trough which is open at the bottom only and which is provided with a means for introducing a gas into the trough. Gas can be introduced into the trough, therefore, to displace the liquid, such that the heat exchange is now between the gas which surrounds the coils and the fluid flowing within the coils.

United States Patent [72] Inventor Robert A. Sauder [56] ReferencesCited [21] A l N 53 x;? Kans- UNITED STATES PATENTS pp o. g i [22] FiledApt 4,1969 3,327,772 6/1967 Kodalra 165/61 [45] Patented June 1, 1971Primary ExaminerCharles Sukalo [73] Assignee Sauder Tank Company, Inc.Attorney-William S. Dorman Emporia, Kans.

ABSTRACT: A heatexchange system involving heatexchange coils adapted tobe immersed in a body of liquid to effect heat exchange through thecoils between the liquid and [54] yfl i 'fix SYSTEM the fluid flowingthrough the coils.v The heat-exchange coils rawmg are covered by aninverted trough which is open at the bottom [52] U.S. Cl 55/269, onlyand which is provided with a means for introducing a gas 165/1, 165/66,165/96 into the trough. Gas can be introduced into the trough, there-[51 Int. Cl BOld 51/00 fore, to displace the liquid, such that the heatexchange is now [50] Field of Search 165/1, 2, between the gas whichsurrounds the coils and the fluid flowing within the coils.

PATENI'EUJUH I III 3,581,475

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J 68 FROM 70 T TO CQLD WELL STREAM SEPARATOR 52/ II I I I T0 PIPE LINEFIG. FROM COLD SEPARATOR ROBERT A. SAUDER 2 INVENTOR.

ATTORNEY PATENEUJUM H97! 7 3.581.475

" 'SHEET 2 o 3 FIG. 3

ROBERT A. SAUDER IN'VENTOR.

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ATTORNEY PATEN I'E-D JUN 1 Ian saw 3 or 3 ROBERT'A. SAUDER IN VENTOR.

ATTORNEY VAlllllABLE HEAT-EXCHANGE SYSTEM The present invention relatesto an improved system of heat transfer and, more particularly, to asystem for varying the heat transfer between a body of liquid which isadapted to selectively surround the coils of a heat exchanger or to bedisplaced therefrom so as to provide, in the first instance, aliquid'fluid heat transfer and in the second instance a gas'fiuid heattransfer.

in the past, where it has been desired to vary the amount of heattransferred to a gas stream, for example, heat-exchange coils carryingthe gas may be embedded in a bath of hot liquid. One method ofcontrolling the amount of heat transferred is to vary the temperature ofthe bath; obviously, such a method would be slow and somewhatineffective. Another method would be to bypass variable quantities ofgas around the heatexchange coil; however, this method requiresadditional piping with attendant increased costs, etc.

I It is a principal object of the present invention to provide animproved heat-transfer system which is simple in operation andrelatively inexpensive to construct and maintain.

It is a further object of the present invention to provide a variableheat-transfer system where, under one condition of operation, theheat-transfer medium surrounding the coils is liquid and, under anothercondition of operation, the heattransfer medium surrounding the coils isgaseous with control means for changing the heat-exchange mediuminstantly from gas to liquid and vice versa.

Other and further objects and advantageous features of the presentinvention will hereinafter more fully appear in connection with adetailed description of the drawings in which:

FIG. 1 is a plan view of one embodiment of the present invention showingthe heat-exchanger assembly in the form of a double-coil heat exchanger;

FIG. 2 is a front elevation of the heat-exchange assembly shown in lFlG.3;

FIG. 3 is a partial sectional view through a gas-treating apparatusemploying the heat-exchange assembly shown in FIGS. )1 and 2;

FIG. 4 is a side elevation of a gas-treating apparatus, with certaininternal portions shown in dotted lines, employing two heat-exchangeassemblies, each of the single-coil type, and adapted to treat twoseparate gas streams; and

H6. 5 is an end elevation of the gas-treating apparatus shown in MG. 41.

Referring to the drawings in detail, the heat-exchanger assembly w shownin FlGS. l and 2 is supported within a vessel 12 (see now PEG. 3)containing a quantity of water M or other suitable liquid. Supported onthe vessel 12 are a horizontal cold separator (high-pressure separator)16 and a vertical low pressure separator 18. The cold separator 16 issupported on the vessel 12 in such a manner that its bottom may contactthe water M within the vessel 12. The upper level of the water isvariable, as will be explained hereinafter, and is indicated by the line2i). The water M is heated by a horizontal furnace or combustion tube 22in any conventional manner.

As best shown in FIGS. l and 2, the heat exchanger is formed by a seriesof horizontal pipes of relatively smaller diameter concentricallydisposed within a series of horizontal pipes of relatively largerdiameter so as to form a central passageway and an annular passageway;that is, inner pipe 24 is concentrically arranged within outer pipe 26.The outer diameter of the inner pipe 2a is somewhat less than the innerdiameter of the outer pipe 26 so as to form an annular space between thetwo pipes. A plug or collar 28 serves to support the inner pipe 24concentrically with respect to the outer pipe 26; this plug 28 alsoserves to seal off the annular space between the two pipes at theforward end of the heat exchanger. A similar plug or collar 30 islocated towards the rear end of the heat exchanger to support the otherend of the pipe 24 concentrically with respect to the outer pipe 26 andalso for the purpose of sealing the other end of the annular space.

Similarly, horizontal pipes 32, M, 36, 38 and lb of relatively smallerdiameter are concentrically supported within horizontal pipes 42, 44,46, 48 and 50, respectively, of relatively larger diameter. Theresulting annular spaces are sealed by the plugs or collars 52, 52, etc.

As best shown in FIG. 2, the tube assemblies are staggered so as to formtwo horizontal rows vertically spaced from each other. Thus, the pipes26, 44 and 48 are in the lower row and the pipes 42, &6 and 50 are inthe upper row. The open adjacent ends of the inner pipes are connectedby means of U shaped pipes 54, as best shown in FIG. 1. The annularspace between the pipe 24 and the pipe 26 communicates with the annularspace between the pipe 32 and the pipe 42 by means of the shortinterconnecting pipe 56. The annular space between the pipe 32 and thepipe communicates with the annular space between the pipe 34 and thepipe 44 by means of the short pipe 58. Successive annular spaces areinterconnected by means of the short pipes (all, 62 and 64 as shown inFIG. 1.

As will appear from the above, a continuous central passageway isprovided through the interiors of the smaller pipes 24, 32, M, 36, 38and 40 in succession, by virtue of the U-shaped connectors 54. Also, acontinuous annular passageway is provided in series around the abovementioned pipes by virtue of the annular spaces created and through theinterconnecting short pipes 56, 58, 60, 62 and 64. Access to one end ofthe closed annular passageway is provided by the short vertical riser 66which connects with the forward end of the pipe 26 leading to theannular space between the pipe 24 and the pipe 26. Access to the otherend of the continuous annular passageway is provided by the shorthorizontal connector 68 which connects with the forward end of the pipe50 and which communicates with the annular space between the pipe 40 andthe pipe 50. Access to the central passageway is achieved simply throughthe forward openings in the pipes 24 and 50.

The heat-exchanger assembly 10 is provided with a front plate 70 towhich is connected an inverted trough 72. The trough 72 is adapted tosurround the heat-exchange tubes. The trough 72 is closed along all thevertical sides and across the top and is open only at the bottom. Aninlet pipe 74 communicates with the upper rear end of the trough topermit air to be introduced to or withdrawn from the inverted trough 72.

Now considering FIGS. 1 and 2 together with FIG. 3, the well stream froman essentially gas-producing well (not shown) enters the short verticalpipe 66 and passes into the continuous annular passageway between theinner and outer pipes. The well stream passes out of the annular areaand into a vertical pipe 76 which connects at its lower end (in anyconventional manner, not shown) with the short horizontal pipe 68 at theother end of the annular passageway. The well stream flows upwardly inthe pipe 76, horizontally to the left in the interconnecting pipe 78,downwardly at an angle through the interconnecting pipe 80, and into thecold separator 16. A choke or expansion device (not shown) is located ator near the inlet 82 to the vessel 16 for the purpose of creating thewell-known pressure drop as the well stream enters the vessel 116. Atemperature-sensing device 84 ("the details of which are not shown) islocated within the pipe b ll so as to sense the temperature of the wellstream immediately prior to entering the vessel 16. A three-way valve 86(the details of which are not shown) is connected to thetemperature-sensing device 8 in such a manner that the position of thevalve 86 is varied in accordance with the temperature sensed. The valve86 connects with a source of air (not shown) and also with theatmosphere. A third port on the valve 86 connects with a horizontal pipe8% which, in turn, connects with a vertical pipe 90, which in turnconnects with the pipe 74 that leads into the inverted trough 72.

The relationships among the valve 816, temperature-sensing device M andpipes 90 and 74% is such that, as the temperature rises above apredetermined value, air will be passed into the inverted trough 72 todisplace hot water therefrom so as to diminish the heat transfer fromthe hot water bath M and incoming well stream flowing through theannular passageway;

conversely, as the temperature falls below a predetermined value, airwill be bled from the inverted trough 72 through pipes 74 and 90 andthrough the valve 86 to the atmosphere. Since the space above the waterline 20 will be at atmospheric pressure, it is possible to fill thetrough 74 completely with water. Preferably, however, the controlarrangement is such that air supply or bleed, as the case may be, willcease as soon as the indicated temperature is achieved at the sensor 84such that trough 72 may be only partially filled with water.

Gas 36 the cold separator 16 passes upwardly through the short verticalpipe 92, horizontally towards the right through the interconnecting pipe94, downwardly through the interconnecting pipe 96 and into the pipe 40through appropriate elbows, etc. The'gas entering the pipe 41) passesinto the central passageway of the heat-exchanger tubes and dischargesfrom the pipe 24 to be sent to the pipe line or other point of use.

FIGS. 4 and show a heat-exchange arrangement adapted to handle the gasproduction from two separate wells. Each incoming well stream,therefore, passes through a separate heatexchange assembly which as willalso hereinafter appear, is of the single-coil type as opposed to thedouble-coil type shown in FIGS. 1 and 2.

The structure shown in FIGS. 4 and 5 includes a vertically extendingrectangular vessel 100 which is adapted to hold a quantity of water 102.The highest water level is indicated by the dotted line 104 and thelowest water level is indicated by the dotted line 106. That is, whenboth heat-exchanger troughs, as will hereinafter appear, are filled withair, the water level will be at line 104; conversely, when bothheatexchanger troughs are filled with water, the water level in thevessel 102 will be at the line 106. As was the case in connection withFIG. 3, the upper portion of the vessel 102 will be at atmosphericpressure.

At either side of the vessel I00, low temperature (high pressure)separators 108 and 110 will be mounted in any conventional manner.Portions of these separators will project into the vessel 100 so as tocontact a portion of the hot water therein. A suitable combustion unit112 will be provided in the lower interior of the vessel 100 so as toheat the water 102. The combustion furnace will be provided with anexternal stack 114.

The heat exchangers and the controls therefor are shownsemidiagrammatically. Lower heat exchanger 116 is shown having an inletpipe 118 and an outlet pipe 120. The central dotted line portionsrepresent parallel horizontal pipes connected at their adjacent ends byU-shaped connectors in a manner similar for that shown in FIGS. 1 and 2.Thus, heat exchanger 1 16 would be provided with a total of sixhorizontal portions extending for the length of the heat exchanger 116.The heat exchanger 116 is also provided with an inverted trough 122closed on all sides except for the bottom which is open. The trough 122is also provided with an inlet opening 124 similar to the inlet pipe 74shown in FIGS. 1 and 2. A conduit 126 connects between the inlet 124 anda control device 128 for the purpose of introducing air to, orexhausting air from, the inverted trough 122. A detailed description ofthe control device 128 is considered to be unnecessary; it shouldsuffice to point out that the control device 128 includes a means forsensing the temperature within the vessel 110 and a valve (preferably athree-way valve) capable of connecting the line 126 to a source of airpressure or to the atmosphere in response to an increase or decrease,respectively, of the temperature within the vessel 110.

A second heat-exchanger assembly 130 is mounted within the vessel abovethe heat exchange assembly 116. The heatexchange assembly 130 isessentially identical to the heatexchange assembly 116 described aboveand includes an inlet pipe 132, an outlet pipe 134, six horizontallengths of pipe within the heat exchanger connected at their adjacentends by U-shaped connectors as represented by the dotted linearrangement, an inverted trough 135, an inlet port 136 connected bymeans of conduit 138 to the control device 1 mounted on the separator1118. The relationship between the inlet 136, the conduit 138 and thecontrol device 140 is the same as that described above in connectionwith the corresponding description of inlet 124, conduit 126 and controldevice 128.

The operation of the device shown in FIGS. 4 and 5 will now bedescribed. The well stream from a first well can enter the heatexchanger 116 through the inlet pipe 118. The well stream makes sixpasses through the heat exchanger 116 and then passes upwardly throughthe pipe into the low-temperature separator 110. A choke (not shown) islocated in the vessel 110 downstream of the inlet 142 where the pipe121) connects with the vessel 110. This choke allows the well stream toexpand somewhat into the vessel 110 thereby lowering the gas temperatureand pressure in a well-known and conventional manner. The gas will leavethe vessel 110 by means of the conduit 144 for subsequent treatment ofthe gas stream.

A well stream from a second well enters the pipe 132 and passes into theheat exchanger making six horizontal passes therethrough emerging fromthe pipe 134 after which the gas passes into the vessel 108. The vessel108 will also be provided with a choke 146 which is downstream of theconnection between the pipe 134 and the vessel 108 for the purpose ofreducing the temperature and pressure of the well stream. The vessel 108will also be provided with an outlet (not shown) for directing the gasto subsequent treatment.

If the temperature within the vessel 110 rises above a predeterminedvalue as determined by the control device 128, the latter will cause airunder pressure to be directed through the conduit 126 and through theinlet 124 into the inverted trough 122 thereby displacing water from theinverted trough and cutting down on the heat transfer between the gasflowing inside the heat exchanger tubes and the water 102 within thevessel 100. Conversely, if the temperature within the vessel 110 fallsbelow a predetermined value as determined by the control device 128, thelatter will connect the conduit 126 to the atmosphere so as to bleed airfrom the inverted trough 122 thereby allowing hot water to enter theheat exchanger 116 to increase the heat transfer effect between the gasflowing in the heat exchanger 116 and the hot water 102.

The manner of introducing air into, and bleeding air from, the invertedtrough for heat exchanger 1311 is substantially the same as that setforth above in connection with heat exchanger 116. That is, the controldevice senses the temperature within the vessel 1118 and, accordingly,forces air into or out of the inverted trough 135.

It should be apparent that the controls for the heat exchangers 116 and1311 are separate and individual; thus, the inverted trough 122 could befull of water while the inverted trough 135 could be full of air, orvice versa. Likewise, both inverted troughs could be filled with air atthe same time or they could be both filled with water at the same time.

Whereas the dual-coil heat exchanger shown in FIGS. 1 to 3 describes theinfluent as passing into the annular area first and later through thecentral area, it should be obvious that the influent could be introducedto the central area first and to the annular area thereafter, if itappeared necessary or desirable to do so.

The heat exchanger shown in FIGS. 1, 2 and 3 on the one hand, and theheat exchangers shown in FIGS. 4 and 5 on the other hand, operate on thesame principle; that is, the heatexchange coils are adapted to beimmersed in a liquid, such as hot water. The heat transfer between thisliquid and the gas flowing through the pipes is at a maximum when theheat exchange coils are totally immersed in the liquid. Conversely, theheat exchange is at a minimum when the heat exchange coils are no longerin contact with the hot water; i.e. when air is introduced into theinverted troughs 72, 122 or 135 to force the water out of the troughs.

Whereas the present invention has been described in particular relationto the drawings attached hereto, it should be understood that other andfurther modifications, apart from those shown or suggested herein, maybe made within the spirit and scope of this invention. For example,although the variable heat transfer has been described above in terms ofa variation in the heat added to the fluid flowing through the heatexchanger, it should be obvious that this variable heat transfer couldtake place under conditions where it would be desirable to cool, orremove heat from, said fluid.

What I claim is:

1. A method of varying the heat transfer between a fluid flowing througha heating coil and a liquid in which the heating coil is immersed whichcomprises surrounding the heating coil within an inverted trough open atthe bottom only, and selectively introducing and withdrawing a gaseousmedium into and from said inverted trough to alternatively displace andpermit entry of, respectively, the liquid from and into said trough.

2. A method as set forth in claim 1 wherein the heating coil is dividedinto a continuous closed central zone and a continuous closed annularzone concentric with said central zone and wherein said fluid isconducted through said heating coil through both zones countercurrently.

3. Apparatus for varying the heat-transfer effect between a fluidflowing in a heating coil and a liquid surrounding the heating coilcomprising a vessel containing a quantity of said liquid, means mountingsaid heating coil in said vessel below the upper level of said liquid,means for introducing said fluid into one end of said heating coil,means for withdrawing said fluid from the opposite end of said heatingcoil, an inverted trough mounted in said vessel surrounding said heatingcoil, said trough being closed along the top and along all sides thereofexcept for the bottom, means responsive to the temperature of the fluidleaving said heating coil for selectively introducing gaseous mediuminto said inverted trough and withdrawing said gaseous medium therefromwhereby said liquid is forced outwardly from said inverted trough inresponse to a first temperature condition and allowed to enter saidtrough under a second temperature condition.

4. Apparatus as set forth in claim 3 wherein said heating coil is formedof a plurality of concentric pipes, one set of concentric pipes beingsupported within a second set of concentric pipes, the outer diameter ofsaid first set of concentric pipes being smaller than the inner diameterof the second set of concentric pipes so as to form annular spacesbetween said two sets of pipes, means connecting the individual annularspaces in series to form a continuous annular passageway, meansconnecting the resulting central spaces together to form a continuouscentral passageway, means for flowing said fluid through said heatingcoil countercurrently through both said passageways.

5. Apparatus as set forth in claim 4 wherein said fluid flowing throughsaid heating coil is a well stream from a gasproducing well and whereinsaid well stream is passed through a low-temperature separator betweenits two passes through the two passageways.

6. Apparatus as set forth in claim 4 wherein said means for flowing saidfluid through said heating coil countercurrently through both saidpassageways includes means for introducing a well stream from agas-producing well into one end of the annular passageway of saidheating coil, means for withdrawing said well stream from the other endof said annular passageway, a cold-temperature separator, means forintroducing the well stream withdrawn from said annular passageway intosaid cold-temperature separator wherein said well stream is allowed toexpand to a lower pressure and lower temperature, means for withdrawinggas from said cold temperature separator, means for introducing the gaswithdrawn from said coldtemperature separator into one end of saidcentral passageway of said heating coil, and means for withdrawing gasfrom the other end of said central passageway of said heat exchanger.

7. Apparatus as set forth in claim 4 wherein said means for flowing saidfluid through said heating coil countercurrently through both saidpassageways includes means for introducing a well stream from afgas-producing well into one end of the central passageway o sax heatingcoil, means for withdrawing said well stream from the other end of saidcentral passageway, a cold-temperature separator, means for introducingthe well stream withdrawn from said central passageway into said coldtemperature separator wherein said well stream is allowed to expand to alower pressure and lower temperature, means for withdrawing gas fromsaid cold-temperature separator, means for introducing the gas withdrawnfrom said cold-temperature separator into one end of said annularpassageway of said heating coil, and means for withdrawing gas from theother end of said annular passageway of said heat exchanger.

1. A method of varying the heat transfer between a fluid flowing througha heating coil and a liquid in which the heating coil is immersed whichcomprises surrounding the heating coil within an inverted trough open atthe bottom only, and selectively introducing and withdrawing a gaseousmedium into and from said inverted trough to alternatively displace andpermit entry of, respectively, the liquid from and into said trough. 2.A method as set forth in claim 1 wherein the heating coil is dividedinto a continuous closed central zone and a continuous closed annularzone concentric with said central zone and wherein said fluid isconducted through said heating coil through both zones countercurrently.3. Apparatus for varying the heat-transfer effect between a fluidflowing in a heating coil and a liquid surrounding the heating coilcomprising a vessel containing a quantity of said liquid, means mountingsaid heating coil in said vessel below the upper level of said liquid,means for introducing said fluid into one end of said heating coil,means for withdrawing said fluid from the opposite end of said heatingcoil, an inverted trough mounted in said vessel surrounding said heatingcoil, said trough being closed along the top and along all sides thereofexcept for the bottom, means responsive to the temperature of the fluidleaving said heating coil for selectively introducing gaseous mediuminto said inverted trough and withdrawing said gaseous medium therefromwhereby said liquid is forced outwardly from said inverted trough inresponse to a first temperature condition and allowed to enter saidtrough under a second temperature condition.
 4. Apparatus as set forthin claim 3 wherein said heating coil is formed of a plurality ofconcentric pipes, one set of concentric pipes being supported within asecond set Of concentric pipes, the outer diameter of said first set ofconcentric pipes being smaller than the inner diameter of the second setof concentric pipes so as to form annular spaces between said two setsof pipes, means connecting the individual annular spaces in series toform a continuous annular passageway, means connecting the resultingcentral spaces together to form a continuous central passageway, meansfor flowing said fluid through said heating coil countercurrentlythrough both said passageways.
 5. Apparatus as set forth in claim 4wherein said fluid flowing through said heating coil is a well streamfrom a gas-producing well and wherein said well stream is passed througha low-temperature separator between its two passes through the twopassageways.
 6. Apparatus as set forth in claim 4 wherein said means forflowing said fluid through said heating coil countercurrently throughboth said passageways includes means for introducing a well stream froma gas-producing well into one end of the annular passageway of saidheating coil, means for withdrawing said well stream from the other endof said annular passageway, a cold-temperature separator, means forintroducing the well stream withdrawn from said annular passageway intosaid cold-temperature separator wherein said well stream is allowed toexpand to a lower pressure and lower temperature, means for withdrawinggas from said cold temperature separator, means for introducing the gaswithdrawn from said cold-temperature separator into one end of saidcentral passageway of said heating coil, and means for withdrawing gasfrom the other end of said central passageway of said heat exchanger. 7.Apparatus as set forth in claim 4 wherein said means for flowing saidfluid through said heating coil countercurrently through both saidpassageways includes means for introducing a well stream from agas-producing well into one end of the central passageway of saidheating coil, means for withdrawing said well stream from the other endof said central passageway, a cold-temperature separator, means forintroducing the well stream withdrawn from said central passageway intosaid cold temperature separator wherein said well stream is allowed toexpand to a lower pressure and lower temperature, means for withdrawinggas from said cold-temperature separator, means for introducing the gaswithdrawn from said cold-temperature separator into one end of saidannular passageway of said heating coil, and means for withdrawing gasfrom the other end of said annular passageway of said heat exchanger.